Aggression

Serotonin and Aggression

• Serotonin inhibits the amygdala, which controls fear, anger, and emotional responses.
• Low serotonin levels impair impulse and aggression control.
• Reduced serotonin affects prefrontal cortex regulation, impacting emotional control and responses to external stimuli.
• Low serotonin leads to impulsivity and difficulty anticipating risks, increasing the likelihood of aggressive behavior.
• Mann et al. (1990) found that depleting serotonin in males increased hostility and aggression.
• Ferrari et al. (2003) showed that rats not allowed to fight had altered dopamine and serotonin levels, raising questions about cause and effect between serotonin and aggression.
• Lindberg et al. (1985) found the lowest levels of serotonin by-product 5-HIAA among violent criminals and those who had attempted suicide, indicating a possible negative correlation.
• Most evidence linking low serotonin levels and aggression is correlational, not causal.

Testosterone and Aggression

• Testosterone is a sex hormone that influences social behavior by affecting emotion and decision-making areas of the brain.
• Higher testosterone levels are associated with increased aggression.
• Men have eight times higher testosterone than women, which contributes to gender differences in aggression levels.
• High testosterone reduces activity in the orbitofrontal cortex, increasing the likelihood of aggressive responses in emotional situations.
• Wagner (1979) showed that aggression decreased in castrated mice and increased with testosterone injections, suggesting a causal link.
• Van Goozen (1997) found that male to female transgender patients became less aggressive when receiving testosterone suppressants, while female to male patients became more aggressive when receiving testosterone.
• Higley et al. (1996) found that individuals with elevated testosterone levels rarely commit aggressive acts, suggesting that social and cognitive factors play a mediating role.
• Dabbs and Morris (1990) found that high testosterone levels had different effects depending on social class.

Limbic System and Aggression

• The limbic system processes emotional responses and is linked to aggressive behavior.
• The frontal cortex controls aggression produced by the limbic system.
• Bard and Mountcastle (1958) found that destruction of the hypothalamus caused permanent aggressive behavior in cats.
• Wong et al. (1997) found that violent male criminals had smaller amygdala volumes.
• Summer's case study showed that a tumor in the limbic system was associated with aggression in a 14-year-old girl.

Genetic Factors: Twin Studies

• If aggression has a genetic component, aggression in one twin should correlate with aggression in the other.
• Monozygotic twins should show a higher concordance rate than dizygotic twins due to sharing 100% of their genes.
• Coccaro et al. (1997) found a 50% concordance rate for criminal behavior in MZ twins versus 19% in DZ twins.
• Christiansen (1977) demonstrated that levels of criminality showed a stronger correlation between identical twins.

The Supermale Theory

• The XYY genotype in males was thought to lead to aggression.
• Court-Brown (1965) suggested XYY patients should be hospitalized due to increased aggression.
• Theilgard (1984) showed that XYY men were slightly more aggressive and less intelligent.

The Warrior Gene (MAOA)

• The MAOA gene affects serotonin reuptake.
• The MAOA-L variant results in a deficiency of the MAOA enzyme, potentially depleting serotonin.
• Brunner (1993) found that aggressive males in a Dutch family had a dysfunctional version of the MAOA gene.
• Godar et al. (2014) showed that MAOA knockout mice displayed increased aggression and lower serotonin levels, which was normalized by fluoxetine.
• Stuart et al. (2014) found that violent men who abused their partners had the faulty MAOA gene.
• Caspi et al (2002) found that boys with the MAOA-L gene who suffered abuse in childhood were more likely to be aggressive as adults.

Ethological Explanation of Aggression

• Ethology studies animal behavior in natural habitats to understand human psychology.
• Conrad Lorenz (1950) viewed aggression as an innate, adaptive drive for survival.

Hydraulic Model

• Creatures build up Action Specific Energy.
• Innate Releasing Mechanisms (IRM) trigger Fixed Action Patterns (FAP).
• After aggression is expressed, the animal is less aggressive until Action Specific Energy builds up again.

Innate Releasing Mechanisms and Fixed Action Patterns

• Innate Releasing Mechanisms prevent the release of aggression until triggered by environmental cues.
• Fixed Action Patterns are sequences of automatic aggressive behaviors that occur when cues are seen.
• Niko Tinbergen described ritualistic aggressive behaviors as Fixed Action Patterns.
• Lea identified five features of FAPs: stereotyped, universal, innate, ballistic, specific.
• Tinbergen (1951) found that male sticklebacks attacked wooden models with a red spot, suggesting the red spot acted as an innate releasing mechanism.

Evolutionary Explanations

• Inherited genes can influence behavior.
• Genes promoting aggressive behavior may be beneficial to reproductive success.

Aggression as an Adaptive Mechanism

• Buss identified adaptations of aggression: self-defense, reputation, achieving status, acquiring resources, preventing infidelity.

Inter-group Aggression

• Buss states human males have evolved cognitive bias towards organised aggression

Intra-group Aggression

• Primarily linked to male rivalry and sexual jealousy.
• Sadalla (1987) showed that women are more physically attracted to men who display dominant behaviour.
• Daley and Wilson (1988) found higher murder rates when female partners were about to leave or just left.

Frustration-Aggression Hypothesis

• Dollard and Miller (1939) state that frustration is any event or stimulus that prevents an individual from attaining a goal.
• Dollard et al. (1939) proposed that frustration leads to aggression, which is a cathartic release.
• Level of aggression depends on desire to achieve the goal, proximity to the goal, perceived likelihood aggression could remove the barrier, reasons for the frustration, and whether the frustration was expected
• Berkowitz (1969) proposed that aggression only occurs in the presence of certain cues, such as weapons.
• Berkowitz (1967) found that participants gave higher levels of shocks in the presence of aggressive cues.
• Green (1968) found that participants who experienced insults gave the highest levels of shocks.

Social Learning Theory and Aggression

• Observational learning can also cause aggression.
• Aggressive acts carried out by a role model will be internalised by an individual and reproduced in the future.
• Likelihood of copying depends on: behavior of the role model, similarity, presentation, warmth, prestige and appropriateness.
• Bandura (1963) demonstrated that viewing aggression led to the modeling of aggressive behavior.
• Onyskiw (2001) found that children who witnessed parental aggression were more frequently aggressive themselves.
• Christianson (2006) studied the Kung San people of the Kalahari Desert and found aggressive behaviour was very rare in this society.

Deindividuation

• Festinger (1952) defined deindividuation as losing the sense of socialized individual identity and engaging in unsocialized behavior.
• Factors increasing deindividuation: large crowds, uniforms, darkness, masks.
• Blumer 1939 defined this as: Circular reaction where the people add to the crowd and the crowd fires up the people which increases the intensity
• Zimbardo (1969) found that students disguised in white coats and hoods were more likely to shock others Supports deindividuation.
• Diener (1976) found that children in a group and anonymous were more likely to steal.
• Gergen (1973) found that participants in a darkened room hugged one another suggesting that deindividuation does lead to the freeing of inhibitions.

Institutional Aggression: Dispositional vs. Situational

• Acts of aggression are more common in prisons than in the outside world.

Dispositional Explanations

• Irwin and Cressey’s (1962) Importation Model suggests that prisoner’s social pasts and personal traits affect the way they behave in prison.

Situational Explanations

• Sykes (1958) proposes that aggression results from environmental deprivations: liberty, autonomy, goods, heterosexual relationships, security.
• Zimbardo (see social influence)
• Wilson set up two units in HMP Woodhill reducing the overcrowding which was a successful way to lower levels of aggression
• Camp & Gaes (2005) found that inmates were just as likely to behave aggressively in low-security prisons as in high-security prisons.
• Poole and Regoli (1983): Violence before prison was the best indicator of violence inside prison. This supports the importation model.
• Fischer (2001) found that segregating gang members inside prison led to a 50% reduction in assaults.

Media Influences on Aggression

• Exposure to aggression in video games and other media may promote aggressive behaviors.
• Ritterfield and Mathiak showed that participants were subjected to a functional magnetic resonance imaging scan whilst playing a violent video game which appeared to suggest that emotional areas of the cortex are to some extent “switched off” during the game.

Desensitization:

• Repeated exposure to violence results in lower emotional reactions to violence.
• Viewing aggression will cause an initiation of this evolved 'fight or flight' response.

Disinhibition

• Disinhibition is when people behave in ways uncharacteristic of normal behaviors as normal constraints against certain behaviours have been weakened by environmental or biological triggers.

Cognitive Priming

• Children as young as ten may have been exposed to 8,000 murders and up to 100,000 other acts of violence on television alone (Huston et al., 1992). Cognitive priming is based on the idea that memory works through association
• A schema is a model of what we think normally happens.
• Cognitive script is a learned way of dealing with a situation.